The invention relates generally to the utility industry and in particular to an apparatus and method for reducing peak loading requirements for a gas utility.
It is well documented for electric utilities that there are peaks in electric power consumption. These peaks generally occur from morning until evening on weekdays, and the cost to the electric utility industry to provide the generating equipment to meet these peak loads is enormous. As a result, many utilities have sought, and in some cases have implemented, variable load pricing wherein the rate structure prices electricity used at different times of the day differently. Thus, electricity used during the peak load hours costs substantially more than, for example, electricity used at night where the load requirement is far below peak.
This rate structure is attractive for the electric utility companies because the cost of generating the incremental power to meet "peak loading requirements" is very expensive. Thus, by diverting energy usage from peak load to shoulder or off-peak times through the differential pricing structure, the electric utilities expect to save significantly by reducing both capital outlay for new plant and equipment, and the ongoing incremental costs of producing the "peak load" electricity.
In addition to the cost savings which are available to a customer by judicious use of electrical appliances, reduced fuel consumption should also be realized by the utility, for example, by using higher efficiency equipment for meeting more of the now shifted electrical load. Also in applications such as electric heat, a differential pricing structure can result in a major fuel savings by inducing customers to reduce the temperature at which a residence or building is maintained, at least during the peak loading periods. Thus a differential pricing policy has major advantages in this time of energy conservation, to inter alia, reduce our dependency upon imported foreign oil and to preserve our present domestic energy supplies.
A similar peak loading situation is well known to the gas utility industry. The gas utility, which contracts for its gas requirements prior to the peak usage season (winter), is supply limited because of the fixed maximum quantity of pipelined gas which can be forced through the available pipeline network. When gas consumption exceeds this "base" level, the gas utility must supplement its relatively cheap "contract gas" with relatively expensive "stored gas", for example, LNG or propane. In this manner the peak loading requirements are met.
Since pipeline or contract gas cannot be readily stored, a peak load substantially always requires that LNG or another available stored gas be used. There has therefore been a need in the gas industry to provide the motivation to encourage gas users to refrain from using gas during the peak times.
Unlike the electric utility industry, however, the peak load times for the gas industry do not occur at the same time each weekday but are seasonal, occurring solely in winter when the residential and commercial use of gas for heating purposes (primarily the residential use) adds to the constant underlying or base commercial and residential use, for example, for hot water. Therefore peak loading times occur substantially solely as a result of increased residential use during those times when the ambient outdoor air temperature is low. For example, the peak usage may start when the outside ambient temperature is about 32.degree. F. Thus, above this threshold temperature, the stored gas supply need not be tapped; whereas below the threshold temperature stored gas supply must be used, thereby significantly increasing the incremental costs to the gas utility. At present, the incremental cost is passed uniformly to all users of natural gas irrespective of the energy saving character of their consumption because there has not, prior to the present invention, been a satisfactory method and apparatus for applying variable rate pricing to gas consumption.
The principle object of this invention is therefore a method and apparatus for urging gas utility customers to refrain from using gas during the peak loading times. Other objects of the invention are a method and apparatus for providing equitable distribution of gas energy costs, for providing a system for incrementally increasing the cost of gas to the major users during peak loading, and for rewarding the frugal user during peak loading. A further object of the invention is an apparatus which is simple to use, which is reliable, which is flexible for use with a multi-level gas pricing system, and which can be employed with existing gas consumption measuring apparatus at minimum costs.